export{

}

abstract class Animal{
    eat(food: string):void{
        console.log(`呼噜呼噜的吃：${food}`);        
    }

    abstract run(distance:number):void;
}

class Dog extends Animal{
    run(distance:number):void{
        console.log(`四脚爬行${distance}`);        
    }
}

const d = new Dog()
d.eat('恩斯马')
d.run(100)